Traveling grates for furnaces have the advantage of being capable of continuous operation with practically all solid fuel materials. The supply of fuel is possible in a convenient manner by pouring it onto the front end of the grate, whereat the fuel ignites due to the burning material which is already on the grate. The continually onmoving grate moves the material slowly in the direction toward the grate end. Following a certain traveling time, fuel is distributed over the entire grate. The speed of movement of the grate is selected by considering the various influencing parameters so that the fuel, upon arrival at the grate end, is burned out. Combustion residues can at the end of the grate fall directly into an ash cart. Combustion residues which fall through the grate along said grate will be moved by the returning strand of the chain toward the feed end and can there be collected by a further ash cart.
The stress of heat on the building material creates problems in traveling grates. The heat performance in relationship to the surface unit of the grate is limited by the heat resistance of the grate material. Due to the great amount of heat stress the lifespan of traveling grates is also limited.
The basic purpose of the invention is to provide a traveling grate of the above-mentioned type such that at a given heat performance per surface unit, the heat stress of the grate material is reduced.
This purpose is attained according to the invention by arranging a system of pipes extending parallel with respect to the upper strand of the rotating chain, which pipes form parts of the grate and are adapted to have a heat absorbing fluid flow therethrough.
In a so-constructed traveling grate, a large amount of heat is discharged within the grate by transfering it to a fluid. Generally, one will use water as a cooling fluid. The pipe system can preferably be connected to a boilerplant, for example can serve to preheat boiler feed water. Other utilizations of the heat which is transferred to the fluid are also possible. Due to the intensive amount of cooling, the grate temperature is reduced as a whole and through this the lifespan of the grate is increased. However, it is also possible to utilize the invention in the sense that at a constant lifespan of the grate in comparison to the noncooled grates, the heat performance of the grate is increased.
A particularly preferable construction is obtained by providing guide flanges on the pipes. It is particularly preferable to form the guide flanges on the pipes. The grate plate guide flanges which are united with the pipes have the advantage of providing a particularly good heat transfer and a simple construction. A very large portion of the discharged heat is conveyed through the portion of the pipe wall into the cooling fluid flowing through the pipes.
In the case of a traveling grate having several parallel chains it is particularly preferable to provide between two chains only one pipe, so that alternately chains and pipes are arranged side by side. However, embodiments also fall within the scope of the invention wherein on one pipe only one guide flange is arranged, so that the number of pipes is twice as great as the number of chains.
All pipes can be connected at their ends by collecting pipes. However, it is also possible to connect only some pipes with one another or each pipe can be supplied separately with fluid. Such an arrangement opens up the possibility of supplying various zones of the grate with varyingly large amounts of cooling fluid.
It is also preferable to provide an additional guide which is associated with the upper strand of the chain. Through this one obtains a particularly exact chain guide, which extends the lifespan of the grate.
Recesses in the grate plates permit an intensive air supply thereby enhancing and enabling a maintaining of the heat performance per surface unit. Combustion air can, however, travel through the spaces between adjacent grate plates.
Advantageous relative and absolute dimensions are not important because, in principle, the inventive traveling grate can be built in almost any size.
The pipes can have various cross sections. A circular cross section is preferable.